Heat exchange units and heating systems employing such units

ABSTRACT

Heat exchange units of the type in which a fluid heat transfer medium is circulated in counterflow relationship through independent flow paths. Heating systems employing such heat exchange units.

llnited State Patent S mm T NW N U w mm d H mm mm m a m Tr m m A k w w mm mWS m a U99 NH 600 53 8 l m% w l 23 6 2 2 3 2 m V d n 0 m m m 3 m OH 5Mm $5 3 mm 00 H36AN I 0. d m N m n n d w Whm .m AR? 1 ll] 2 25 W URNPrimary ExaminerCharles Sukalo HEAT EXCHANGE UNITS AND HEATINGAll0rney-Strauch, Nolan, Neale, Nies & Kurz SYSTEMS EMPLOYING SUCH UNITSABSTRACT: Heat exchange units of the type in which a fluid heat transfermedium is circulated in counterflow relationship through independentflow paths. Heating systems employing 5 82 7 mm d6 6 l 1 I F a a m .W"n" F mmm g "H" .m mmm mm." D mm 5 mmw muus lun .I h s h ZUImF ll] 2 0555 PATENTEDuuv 23 Ian I v r lH H I I I I I HH H H Hl l l I lwlll ll llrI I V IH I'IHHHHHHHI HI IIHHHHHIHHHH SHEEI 1 UF 2 INVENTOR HORACE L.SMITH,JR.

ATTORNEYS HEAT EXCHANGE UNITS AND HEATING SYSTEMS EMPLOYING SUCH UNITSThis invention relates to heat exchange. In one aspect this inventionrelates more specifically to novel, improved press platens or likedevices. In another aspect the invention relates to novel systems forcirculating a fluid heat transfer medium through such devices.

Press platens and similar heat exchangers are used in apparatus designedto dry or otherwise heat or cool a variety of materials such as veneers,wallboard and the like, laminates of various kinds, etc. Exemplary heatexchangers of the type with which the present invention is concerned aredisclosed in U.S. Pat. Nos. 1,097,223 issued May 19, 1914; 1,754,853issued Apr. 15, 1930; 1,828,477 issued Oct. 20, 1931; 2,217,652 issuedOct. 8, 1949; 2,572,972 issued Oct. 20, 1951; 1,627,290 issued Feb. 3,1953; 2,699,325 issued Jan. 11, 1955; 3,055,642 issued Sept. 25, 1962;3,064,363 issued Nov. 20, 1962; and 3,206,829 issued Sept. 21, 1965.

Another heat exchanger of this general type is disclosed in my U.S. Pat.No. 3,181,605 issued May 4, 1965. In the heat exchangers disclosed inthat patent there is countercurrent flow of the heat exchange mediumthrough two internested flow channels in the body of the device.Accordingly, such heat exchangers have a generally uniform temperatureacross their entire surface, which is a highly desirable attribute.

l have now invented novel heat exchangers such as press platens and thelike which have the advantages of those disclosed in my earlier patent,but which have greater rigidity and even more uniform surfacetemperatures. In general, these novel heat exchangers consist of a bodyof heat-conductive material in which a series or row of parallel,spaced-apart conduits are formed. These conduits are blind-ended, andalternate conduits open onto opposite sides of the heat exchanger body.Dividers in the conduits, plugs in the open ends of the conduits, andlongitudinal channels communicating with the conduits at their open endscooperate with the conduits to provide two internested, serpentine flowpaths in the body of the heat exchanger through which a heat exchangemedium can be circulated in counterflow relationship.

Because of the relatively heavy sections of heat-conductive materialaround the flow conduits, excellent heat equilization is obtained byconduction in the novel heat exchangers of the present invention.Accordingly, such heat exchangers have highly uniform surfacetemperatures.

Also, because of this relatively massive construction, the heatexchangers of the present invention are extremely rigid and inflexible.This is very advantageous, especially in those applications requiringuniform pressure on the article or material being heated.

Another advantage of the novel heat exchangers described herein is thatthey can be manufactured without welding. This permits the body to bemade of materials such as gray cast iron which are extremely difficultto weld but have excellent rigidity and heat conduction and can bemachined to the very close tolerances typically required in applicationswhere press platens and the like are employed.

As pointed out in my issued patent U.S. Pat. No. 3,181,605, a number ofadvantages can be obtained by employing high boiling point liquids asthe heat transfer media for press platens and the like rather than steamas is conventionally done. These include the elimination ofsuperatmospheric pressures and the equipment required when suchpressures are involved. Also, nonuniform heating is common when steam isemployed in press platens and the like due to the presence of air in thesteam and the uneven collection of condensate in the platen which canoccur if the heat exchanger is not exactly level.

In another aspect the present invention relates to a novel system forsupplying high boiling point liquids to heat exchangers of the typedescribed herein. Another feature of this heating system is anarrangement by which the heat transfer liquid can be cooled andcirculated through the heat exchanger where cooling or both heating andcooling are required.

One important and primary object of the present invention is theprovision of novel, improved heat exchangers such as press platens andthe like.

Another important and primary object of the present invention residesinthe provision of heat exchangers which have the advantages of but areimprovements over those disclosed in my issued patent U.S. Pat. No.3,181 ,605.

Still other related and important but more specific objects of theinvention reside in the provision of heat exchangers, which:

1. have highly uniform surface temperatures when heated.

2. are highly rigid and inflexible.

3. can be fabricated from materials which are difficult to weld, butotherwise have desirable properties.

4. have various combinations of the foregoing attributes.

Yet another important object of this invention resides in the provisionof novel systems for heating and/or cooling and sup-. plying a liquidheat transfer medium to heat exchangers such as press platens and thelike.

Other important objects and advantages and further novel features of thepresent invention will become apparent from the appended claims and asthe ensuing detailed description and discussion of the inventionproceeds in conjunction with the accompanying drawing in which:

FIG. 1 is a plan view of a press platen type heat exchanger constructedin accord with the principles of the present invention;

FIG. 2 is an end view of the heat exchanger;

FIG. 3 is a partial horizontal section through the heat exchanger;

FIG. 4 is a partial section through the heat exchanger takensubstantially along line 4-4 of FIG. 3; and

FIG. 5 is a system in accord with the present invention for heatingand/or cooling a liquid heat transfer medium and circulating it througha heat exchanger.

Referring now to the drawing, FIG. 1 depicts in schematic form anexemplary heating system 8 in accord with the present invention, whichincludes a heating unit 10, a cooling unit 12, a press platen l4incorporating the principles of the present invention, and a closedsystem of conduits and controllers for circulating a liquid heattransfer medium at a specified temperature through platen 14.

Referring now to FIGS. 1-4, the novel press platen l4 referred to aboveincludes a body 16 in which a row of laterally extending, parallel,spaced-apart conduits 18 extending generally from one side of body 16 tothe other is formed as by rifle drilling. Body 16 will typically beformed from gray cast iron, which is a good heat conductor and has highstrength and rigidity. The body 16 ofa typical press platen will be 8feet long, 4 feet wide, and 2 inches thick. Conduits 18 will typicallybe on the order of 1 inch in diameter.

Referring now specifically to FIG. 1, each of the conduits 18 has anopen end and a blind end. Alternate conduits open onto opposite sides 20and 22 of body 16.

As shown in FIG. 1, the lateral conduits 18 opening onto side 20 of body16 communicate with a conduit 24 extending longitudinally through thebody. The conduits 18 opening onto the opposite side 22 of the bodysimilar communicate with a conduit 26 also extending longitudinallythrough the body 16 of press platen 24. The open ends of conduits 24 and26 are closed by plugs 27 threaded into or welded or otherwise fixed tothe body 16 of press platen 14.

Turning now to FIGS. 1 and 3, the open ends oflaterally extendingconduits 18 are closed by plugs 28. Extending from each plug 28 throughthe associated conduit 18 and terminating short of the blind end 30 ofthe conduit is a divider 32. As shown in FIGS. 1, 3 and 4, dividers 32divide each of the flow conduits 18 into two adjacent flow paths 34aand34b, which communicate at the blind end 30 of the conduit.

Referring now specifically to FIG. 1, the flow path 34a in each of theconduits 30 communicates with the flow path 34b in the next conduitopening onto the same side of press platen body 16 through thelongitudinal conduit 24 or 26 with which these conduits l8 communicate.

The arrangement just described provides in body 16 two serpentine,internested flow paths 36 and 38 extending generally from end-to-end ofpress platen body 16 with the legs of the flow paths substantiallyspanning the platen body.

The liquid heat transfer medium is circulated in counterflowrelationship through flow paths 36 and 38. This is accomplished byintroducing the heat transfer medium into flow path 36 through inlet 40and discharging it through outlet 42 while introducing the heat transfermedium into flow path 38 through inlet 44 and discharging it throughoutlet 46.

One of the novel features of the present invention resides in employinga high boiling point liquid as the circulating medium, permitting it tobe circulated at extremely high temperatures in liquid form.Consequently, the using units may be heated to high temperatures and yetthe system components need be designed to withstand only very lowpressures. Suitable heat transfer liquids include Aroclor 1248 achlorinated bi-phenyl) and lsopropyl Santowax (a polyphenyl alkyl),which are produced by Monsanto Chemical Co., and XFl-014 (an aryloryloxy silone manufactured by Dow Chemical Company). Aroclor 1248liquid may be heated to temperatures on the order of 550-570 F. withoutboiling and without exceeding a permissive rate of decomposition rate ofslightly less than 0.00l percent per hour of operation. Since a buildupof decomposition products of approximately 20 percent can be toleratedbefore pumping costs become excessive, the same liquid may be used forabout 3 years without replacement (a system of the type to which thepresent invention relates normally operates on the order of 7,000 hoursper year).

If the medium is to be heated to higher temperatures, lsopropyl Santowaxor XFl-l84 may be employed. lsopropyl Santowax liquid can safely beheated to temperatures of about 700 F. At 700 F., this liquid hassubstantially the same rate of decomposition that Aroclor 1248 has at550 F. XFl-l84 can be used at temperatures up to about 800 F. At 700 F.XFl- 0l84 has substantially the same rate of decomposition as lsopropylSantowax at the same temperature.

Referring now to FIG. 5, the heat transfer liquid is introduced into theclosed circulating system from a storage tank 47 which is connected byconduit 48 to return conduit 50 of the main circulating system. Areversible pump 52 is interposed in conduit 48 to force the liquid intothe return conduit and to return it to storage tank 47 if it becomesnecessary to drain the system, A manual valve 54 in conduit 48 may beopened to allow the liquid to be pumped from storage tank 47 into thesystem and closed to prevent discharge of the liquid back into thestorage tank after the system is filled. A drain valve 55 will alsotypically be provided so that system 8 can be drained when necessary.

The main circulating pump 56 interposed in return conduit 50 pumps theliquid through the return conduit into heating unit 10. Pump 56 can beisolated by closing valves 57a and 57b in main return conduit 50,

An expansion tank 86 is connected into main return conduit 50 by abranch conduit 88. This tank 86 accommodates expansion of liquid in theclosed system, preventing abnormal pressure conditions from burstingconduits or other system components, and maintains a gravity head on thesystem.

In the expansion tank is a valve (not shown) operated by a float 90,which controls flow through an outlet line 92. If, under some abnormaloperating condition, the level of the liquid in expansion tank 86 shouldrise to a dangerous level, float 90 will open the valve, allowing excessliquid to be discharged through outlet line 92 to prevent rupture orbursting of system components.

An indication of the pressure in the circulation system is furnished bypressure gages 58 and 60 interposed in main return conduit 50 on theinlet and discharge sides of the main circulating pump 56. Pressuregages 58 and 60 provide a ready indication of conditions detrimental tocirculation such as blockage ofa flow conduit or the like.

The end of main return conduit 50 is connected to the inlet of heatingunit 10. As illustrated, heating unit includes sinuous heating tubes 62(one of which is shown) through which the circulating medium flows andover which hot gases generated by combustion units 64 pass. Heatingtubes 62 and combustion units 64 are housed in an outer shell 66 ofconventional construction which is preferably lined with an appropriaterefractory (not shown) to radiate heat to heating tubes 62. Thecombustion units 64 may be either gas or oil burners or, if heating unit10 is of larger capacity, may be coal fired.

Fuel flows to combustion units 62 through an inlet line 68 in which isinterposed an automatically controlled valve 70. Valve 70 is preferablycontrolled by a conventional temperature-responsive controller 72responsive to the temperature of the circulating medium discharged fromthe heating tubes 62 in heating unit 10 to insure that the circulatingmedium discharged from the heating unit is at the correct temperature.

The outlets of heating tubes 62 are connected to the main' supplyconduit 73. The heated circulating medium flows through this conduit toheat using unit 14* or, if there is no demand for heat, from thisconduit directly through conduit 74 and normally closed valve 76 intomain return conduit 50. mmber of heating using units will be suppliedfrom a single heating unit 10. Only one heat using unit is shown for thesake of clarity.

When there is a requirement for heat in heat exchange unit 14, valve 78is opened; valve 76 is closed; and the heated liquid is pumped throughmain supply conduit 73 to branch supply conduits 79 and 80. Branchsupply conduit 79 is connected to the inlet 40 to flow path 36 throughpress platen l4, and branch supply conduit 80 is connected to the inlet44 to flow path 38.

The outlet 42 from flow path 36 is connected to a branch return conduit82, and the outlet 46 from flow path 38 is connected to a branch returnconduit 84. These branch return conduits are in turn connected to mainreturn conduit 50. Thus, when there is a demand for heat, heated liquidis circulated from heating unit 10 through main supply conduit 73 andbranch supply conduits 79 and 80 to the heat-using unit 14, through theflow paths 36 and 38 in that unit, and then through branch returnconduits 82 and 84 and main return conduit 50 back to the heating unit.

Notwithstanding the variation in demand for heat transfer liquid atpress platen 14, a reasonably constant high-velocity flow, preferably onthe order of about 8 feet per second, must be maintained through themain circulating system for, ifconstant circulation is not maintained,the medium in the heating tubes 62 of heater 10 will be overheated andwill polymerize, forming a thick sludge which will adversely affect theperformance of the system when heat transfer liquids such as thosedescribed above are employed.

In order to maintain this flow substantially constant, a valve 94 isconnected in main return conduit 50. Valve 94 is controlled by apressure controller 96 responsive to the pressure in main return conduit50. Valve 94 functions as follows: if the circulating medium is divertedfrom main supply conduit 73 into the heat-using unit 14 in the mannerdescribed above, this diversion of circulating medium from the mainsupply conduit will be detected by the sensing element of pressurecontroller 96 which will open valve 94 more widely, increasing the flowarea through it to compensate for the diversion of circulating mediuminto the unit when the demand for additional heat exists. As the demandfor additional heat by the heat-using unit is satisfied, less of thecirculating medium will be diverted through it. This condition will bedetected by pressure controller 96 which will decrease the flow areathrough valve 94 to compensate for the diminishing diversion of thecirculating liquid to the heat-using unit. Thus, by taking advantage ofthe known flow law that quantity of flow is directly proportional to theflow area and the pressure drop through a closed circulating system,pressure regulated valve 94 maintains substantially constant flowthrough the main circulating system.

Notwithstanding the precautions taken to insure constant flow throughthe main circulating system, stoppage in the supply or branch conduitsmay occur, decreasing or even completely blocking flow through the mainsystem and leading to overheating and polymerization of the circulatingmedium. To prevent a flow stoppage in the main circulating system formhaving this adverse effect, a novel bypass circuit arrangement,including a bypass conduit 98 connected between main supply conduit 73adjacent the discharge end of heating unit and to main return conduit 50on the inlet side of main circulating pump 56, is provided. Flow throughbypass conduit 98 is controlled by a valve 100 which, in turn, isregulated by a differential pressure controller 102, the twobellows-type sensing elements of which (not shown) are connected byleads 104 and 106 to the discharge and inlet sides of main circulatingpump 56. Differential pressure controller 102, which may be of anyconventional construction such as the Differential Pressuretrolmanufactured by Minneapolis Honeywell Regulator Co., takes advantage ofthe well-known fact that, if a constant differential is maintainedbetween the suction and discharge pressures of a pump, the volume ofliquid circulated by the pump will remain constant.

Therefore, should a condition arise tending to resist the flow throughthe system, the differential between the suction and discharge pressureswill increase. In this circumstance, differential pressure controller102 will open bypass valve 100, allowing the circulating medium to flowfrom main supply conduit 73 through bypass conduit 98 into main returnconduit 50, maintaining the flow of liquid through heating unit 10constant and thereby preventing the circulating medium from overheating.

When the resistance to the flow of fluid through the main circulatingsystem is removed, the differential between the pump suction anddischarge pressures will decrease. Differential pressure controller 102will then close bypass valve 100, decreasing the flow of liquid throughbypass conduit 98 and increasing the flow through the main circulatingsystem.

Another important function is also served by the bypass arrangement justdescribed. When the system is started up, it is preferable to bring thecirculating medium to operating temperature as quickly as possible. inthis circumstance, differential pressure controller 102 is set to openbypass valve 100 so that a substantial portion of the liquid in thecirculating system will flow directly through bypass conduit 98 backinto heating unit 10, quickly raising the circulating medium tooperating temperature.

As mentioned above, provision is also preferably made in heating system8 for cooling the heat exchange liquid before it is circulated to pressplaten 14 so that the platen can be used for cooling as well as heating,The components provided for this purpose include cooling unit 12, whichis a conventional heat exchanger having tubes 108 (only one of which isshown), through which the heat exchange liquid flows, and a shell 109through which a coolant is circulated. The heat exchanger is connectedby supply and return conduits 110 and 112 to main supply and returnconduits 73 and 50. A pump 1 14 is provided to circulate the heatexchange liquid through a closed path including heat exchanger 12,supply conduits 110, 73, and 79 and 80, press platen 14, and returnconduits 82 and 84, 50, and 112. Pressure gages 116 and 118 on oppositesides of pump 114 provide an indication of flow conditions in the closedcirculation path just described.

When there is a demand for a reduced temperature at press platen 14,valves 78 and 94 in main supply and return conduits 73 and 50 areclosed, valves 120 and 122 in the conduits 110 and 112 connecting heatexchanger 12 to the main supply and return conduits are opened, and pump114 is started to circulate the heat transfer liquid through the pathdescribed above. As the heat transfer liquid flows through the tubes 108of heat exchanger 12, its temperature is reduced by water or othercoolant which flows to the heat exchanger through conduit 124,circulates through the shell 109 of the heat exchanger, and dischargesthrough conduit 126, the flow being controlled by a valve 127 in conduit124. The lower temperature liquid then flows to press platen 14 toreduce its temperature.

in the operational mode of heating system 8 just described, expansiontank 86 is isolated from the circulation system. Ac-

cordingly, a second expansion tank 128 equipped with an outlet line 130and a float-controlled valve (not shown) is preferably connected toconduit 112 through a conduit 134. This arrangement functions in thesame manner as that described above and is provided for the samereasons.

Heating systems of the type just described will typically have othercomponents such as systems for pumping the heat transfer liquids at adifferent rate through each of a plurality of heat exchangers and anarrangement for preventing overheating of the heating unit when thesystem is shut down. These and other system components are described inmy US. Pat. No. 3,236,292, which is hereby incorporated herein.

For applications where temperatures higher than those obtainable by theheat transfer liquids described above may be advantageously utilized,eutectic mixtures of organic salts such as HTS may be employed as theheat transfer medium. In this case modifications such as those describedin my US. Pat Nos. 3,258,204 issued June 28, 1966 and 3,329,344 issuedJuly 4, 1967, may be made in the exemplary press platen or heatingsystem described above or in both of the foregoing.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description; and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent 1s:

1. A heat exchange unit such as a press platen or the like, comprising abody of heat-conductive material; a row of parallel, spaced-apart,lateral passages formed in said body, said passages extending generallyfrom one side of said body to the other side thereof and each of saidlateral passages having an open end and a blind end with alternatepassages having their open ends at opposite sides of said body; dividermeans in and extending generally the length of each lateral passage butterminating short of the blind end thereof for dividing the passage intotwo connected flow channels; a longitudinally extending passage formedin said body at each side thereof, those lateral passages having theiropen ends at one side of said body all communicating at said open endswith one of said longitudinally extending passages, the remainder ofsaid lateral passages all communicating at their open ends with theother of said longitudinally extending passages, and the longitudinallyextending passages cooperating with the divider means to so providefluid communication between the flow channels in the lateral passagesopening onto one side of said body as to provide a first serpentine flowpath extending generally from end to end of the press platen body andbetween the lateral passages opening onto the other side of said body toprovide a second serpentine flow path internested with the first flowpath; and means for effecting flow of a fluid heat transfer medium incounterflow relationship through said first and second flow paths tothereby change the temperature of the press platen body.

2. A heat exchange unit such as a press platen or the like, comprising abody of heat-conductive material; a row of parallel, spaced-apart,lateral conduits formed in said body, said row of conduits extendinggenerally from one side of said body to the other side thereof and eachof said lateral conduits having an open end and a blind end withalternate conduits opening onto opposite sides of said body; plugsfitted in the open ends of said conduits to prevent the escape of fluidtherefrom; divider means in each of said lateral conduits for dividingthe conduit into two connected flow channels, said divider means beingfixed at one end thereof to the plugs in the same lateral conduits toprevent short circuiting of the heat exchange medium between the lateralconduits and the opposite ends of said divider means terminating shortof the blind ends of the conduits in which they are disposed to providethe fluid communication between the two flow channels in each of saidconthe sides of the body, each of said longitudinal conduitscommunicating with the lateral conduits opening onto the side of thebody in which the longitudinal conduit is formed; and means foreffecting flow of a fluid heat transfer medium in counterflowrelationship through said first and second flow paths to thereby changethe temperature of the press platen body.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 I 909Dated November 23 1971 Inventor(s) Horace L. Smith, Jr.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 16, change "1,627,290" to --2,627,290--.

Column 2, line 61, change "24" (first occurrence) to --l4.

Column 5, line 3, change "form" to --from--.

Patent should have issued in the name of SMITHERM INDUSTRIES,

INC. Assignment recorded 4/29/71, Reel 2733,

Frame 326.

Signed and sealed this 26th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM O-1 50 -6 USCUMM-I/(I WINE-P61:

u S LOVEIINMFNY vwmnm mull Win1- 101, an

1. A heat exchange unit such as a press platen or the like, comprising abody of heat-conductive material; a roW of parallel, spaced-apart,lateral passages formed in said body, said passages extending generallyfrom one side of said body to the other side thereof and each of saidlateral passages having an open end and a blind end with alternatepassages having their open ends at opposite sides of said body; dividermeans in and extending generally the length of each lateral passage butterminating short of the blind end thereof for dividing the passage intotwo connected flow channels; a longitudinally extending passage formedin said body at each side thereof, those lateral passages having theiropen ends at one side of said body all communicating at said open endswith one of said longitudinally extending passages, the remainder ofsaid lateral passages all communicating at their open ends with theother of said longitudinally extending passages, and the longitudinallyextending passages cooperating with the divider means to so providefluid communication between the flow channels in the lateral passagesopening onto one side of said body as to provide a first serpentine flowpath extending generally from end to end of the press platen body andbetween the lateral passages opening onto the other side of said body toprovide a second serpentine flow path internested with the first flowpath; and means for effecting flow of a fluid heat transfer medium incounterflow relationship through said first and second flow paths tothereby change the temperature of the press platen body.
 2. A heatexchange unit such as a press platen or the like, comprising a body ofheat-conductive material; a row of parallel, spaced-apart, lateralconduits formed in said body, said row of conduits extending generallyfrom one side of said body to the other side thereof and each of saidlateral conduits having an open end and a blind end with alternateconduits opening onto opposite sides of said body; plugs fitted in theopen ends of said conduits to prevent the escape of fluid therefrom;divider means in each of said lateral conduits for dividing the conduitinto two connected flow channels, said divider means being fixed at oneend thereof to the plugs in the same lateral conduits to prevent shortcircuiting of the heat exchange medium between the lateral conduits andthe opposite ends of said divider means terminating short of the blindends of the conduits in which they are disposed to provide the fluidcommunication between the two flow channels in each of said conduits;means providing fluid communication between the flow channels inadjacent ones of the conduits opening onto one side of said body toprovide a first serpentine flow path extending generally from end to endof the press platen body and between the conduits opening onto the otherside of said body to provide a second serpentine flow path internestedwith the first flow path, the means providing communication between theflow channels in adjacent conduits comprising longitudinal conduitsformed in said body which extend along and adjacent the sides of thebody, each of said longitudinal conduits communicating with the lateralconduits opening onto the side of the body in which the longitudinalconduit is formed; and means for effecting flow of a fluid heat transfermedium in counterflow relationship through said first and second flowpaths to thereby change the temperature of the press platen body.